Cam clamp for back wiring connection



Sepia H, 15$ H. HUBBELL CAM CLAMP FOR BACK WIRING CONNECTION 2 Sheets-Sheet 1 Filed Jan. 24, 1952 C 3 K I Z 45? 6., 5- Y mwemor mi'omegg l g 1956 I H. HUBBELL 2,763,847

CAM CLAMP FOR BACK WIRING CONNECTION Filed Jan. 24, 1952 2 Sheets-Sheet 2 III 3 Ennentor 227 119; fi w;

United States Patent CAM CLAMP FOR BACK WIRING CONNECTION Harvey Hubbell, Long Hill, C0nu., assignor to Harvey Hubbell, Incorporated, Bridgeport, Comm, a corporation of Connecticut Application January 24, 1952, Serial No. 267,946

6 Claims. (Cl. 339-219) This invention relates to a wiring connection for electrical wiring devices, and more particularly to a socalled back wiring connection for such devices, and has for an object to provide an improved means for connecting lead wires to electrical wiring devices in which the wires or leads are inserted through openings in the insulating body of the device from one side and secured to contacts or other conductor elements at the other side of the electrical device, and in which the wires are secured by a simple operation of merely turning a clamping element, eliminating the use of the ordinary binding post screws now commonly employed and doing away with the necessity of winding the stripped ends of the wires about the shanks of the screws prior to tightening them up for the securing operation.

Another object is to provide a connecting means for the lead Wires which comprises a simple cam clamping element which, after the wire has been inserted to the proper position, is merely set up by a screw driver or the like to securely clamp the lead wire and connect it to the electrical contact or other element.

With the foregoing and other objects in view, I have devised the construction illustrated in the accompanying drawings forming a part of this specification. It is, however, to be understood the invention is not limited to the specific details of construction and arrangement shown, but may embody various changes and modifications within the scope of the invention.

In these drawings:

Fig. 1 is a view of the outer face of an attachment plug cap embodying this invention;

Fig. 2 is a side view with parts broken away to more clearly show the construction;

Fig. 3 is a view looking from the right of Fig. 2 with one of the contacts removed;

Fig. 4 is a transverse section substantially on line 44 of Fig. 3;

Fig. 5 is a section substantially on line 5-5 of Fig. 3 and showing the anchoring element in elevation;

Fig. 6 is a detail section substantially on line 6-6 of Fig. 3 showing the contact blade and its securing means in elevation;

Figs. 7, 8 and 9 are a top plan, side elevation and bottom plan view respectively of the base member;

Figs. 10 and 11 are top and side views respectively of the cam element;

Fig. 12 is an end view of an attacment plug cap showing a modified construction and with one of the contacts removed;

Figs. 13, 14 and are detailed sections substantially on lines 13-13, 14--14, and 1515 respectively of Fig. 12;

Fig. 16 is a side view of the electrical contact of Figs. 12 to 15;

Fig. 17 is an end view thereof looking from the left of Fig. 16;

Fig. 18 is a similar view looking from the right of Fig. 16, and

Figs. 19 and 20 are a top plan view and a longitudinal section respectively of the cam element used in the form of Figs. 12 to 15.

Referring first to the form of the device shown in Figs. 1 to 11, the wiring connector is shown by way of example as applied to an attachment plug cap for plugging in electrical attachments to outlets or receptacles in a house or similar wiring system, but it is to be understood the wire connector means may be used in various electrical wiring devices.

The attachment plug cap shown comprises a body member 1 of insulating material enclosed in a metal protecting shell 2 which is generally cup-shaped including a bottom or end wall 3 over one side of the body member and side walls 4 embracing side walls of the body member. Associated with the casing may be employed a strain release clamp comprising laterally shiftable clamping members 5 transversely curved as shown in Fig. 1 to grip the opposite sides of an insulation covered conducting cord 6 by means of connecting screws 7. This clamping means, however, is not claimed as part of the present invention, but is the same as that disclosed in my prior application Serial No. 245,607, filed September 7, 1951.

The end wall 3 of the shell has an opening 8 through which the end of the insulated conductor cord 6 enclosing the lead wires may be inserted, and this opening leads to a plurality of openings or passages 9 passing through the body member 1 to the opposite side thereof. The inlet side of these openings may be enlarged and tapered as shown at 9a to facilitate insertion of the end of the Wire and also to receive the end of the insulation 11a on the Wire. The body 1 is provided in its opposite surface with suitable recesses Ill in which are mounted the electrical terminals or contacts to which the stripped or bated ends of the conductor or lead wires are connected, one of these wires or bundles of fine wires being shown at 11 in Fig. 2, and clamped to one of the electrical contacts.

The electrical contacts as shown in Figs. 3 and 6 to 9 comprise a base member 12 of generally U-shaped cross section, as indicated in Fig. 8, including a top or outer base plate 13 forming one leg of the U shape, and an inner or lower ear or lug 14 secured to one edge of the plate 13 and spaced therefrom by a connecting wall 15, and forming the other leg of the U shape. Both the plate 13 and the member 14 are provided with aligned openings 16 and 17 for insertion of the bared end 11 of the lead wire, and spaced laterally to one side of this opening are aligned openings 18 and 19 in the members 13 and 14. The adjacent sides of openings 16 and 18 are open and connected as shown at 18a. Mounted in this member between the plate 13 and the ear 14 is a clamping cam member 20, and on the back or inner side of this member is a lug 21 having a good turning it in the opening 19 and passing through this opening into a similarly shaped recess or socket 22 in the insulating body 1 at the bottom of the depression ltla in the bottom wall of the recess 10. This recess or socket 22 therefore forms a pivotal mounting for the cam 20 in the insulating body, and the opening 19 forms a pivotal mounting for this cam in the base member 12, the enlarged head portion 23 being located between the plate 13 and the car 14 as shown in Fig. 2, and thus when the base 12 is mounted in the recess 10 the cam is held in position by the base 12. This cam has an eccentric curved cam surface 24 on its outer edge which is located to one side of the openings 16 and 17, and the top surface is provided with a transverse groove or channel 25 to receive the bit of a screw driver or similar tool for turning the cam in its mounting, this channel being exposed through the opening 18 in the plate 13 to give access to this channel for manipulation of the cam. The opening 18 is smaller than the cam so the cam is held in position by plate 13. The base member 12 is mounted in the recess '10 with the openings 16 .and 17 in alignment with the openings 9 in the body member 1, and -it is secured to the body member by .any suitable means such, for example, as an anchoring rivet 26 having a roughened or knurled end portion'27 molded in the body member 1 to anchor it therein in a suitable position in the bottom of the recess with its outer end 28 passing through an opening 29 in the plate 13, which plate rests on top of a flange 30 of this rivet, and the end of the rivet then being swaged or rolled over as shown at 31, to anchor the member 12 to the body member. This rivet may-also be used to secure a contact blade 32 to the base member 12 in position for insertion in an entrance slot in an outlet connector or outlet receptacle to engage an electrical contact in the receptacle, in which case the blade 32 has an angular base plate 33 at its inner end seated on the plate 13 and provided with an opening through which the end 28 of the rivet extends, so that when this end of the rivet is 'swaged -or rolled over it has the double function of securing the contact blade to the base member 12 and also mounting both of these members in the recess in the body member, or if preferred, the contact blade 32 could be an integral part of the base plate 13, which arrangement is common in attachment plug caps.

In making a connection of the lead wire 11 to the base member 12 the cam is turned backwardly so that its cam surface lies to one side of the aligned openings 17 in the base member 12. This leaves these openings free for insertion of the stripped or bared end 11 of the lead wire, as shown in Fig. 2, and then the cam is rotated so that its eccentric cam surface 24 presses against the side of the lead wire and securely clamps it against the inner side of the connecting wall 15 and the opposite sides of the openings 16 and 17 from the cam. This cam surface is of -a pitch or eccentricity such that it securely clamps the lead wire, but after being shifted to the clamping position the pressure against the cam from the lead wire will not tend to turn the cam to release the wire, because the centers of the openings 16 and 17, and therefore the center of the wire and the center of rotation of the cam on pivot lug 21 are in alignment, as shown in Fig. 7, and the line joining the-centers of openings 16 and 17 and the center of cam pivot 21 is at right angles to the clamping wall. Therefore, in clamping the lead wire all that is necessary after the end of the wire 11 is inserted through the openings 16 and 17 is to turn the cam to the clamping position to securely clamp the wire. The cam may also be a close fit between the plate 13 and the ear 14 and the pivot stud 21 in the opening 19 and recess 22 to further assist in retaining it in the clamped position and against accidental turning to release the wires. To release the wire, if desired, all that is necessary is to turn the cam backwardly to released position.

In the modified construction of Figs. 12 to 20, the body member of insulating material is shown at 34 and may be enclosed in a similar shell as in the first form, a portion of a side wall 4 being shown at the outer side of the body member. A face of the body member is provided with recesses 35 corresponding with the recesses 10 of the first form, and in'which the contact elements are mounted, the body member being provided with openings or passages 36 extending through it from the opposite side, one for each recess, for insertion of the bared ends 11 of the lead wires, and the entrance side may be tapered outwardly as shown at 37 to facilitate insertion of the lead wire and also to receive the end of the insulation 11a on the wire adjacent the stripped end. The electric contacts including the contact blade and mounting therefor in this form of thexdevice are formed ofa one-piece integral structure, asshown more clearly in Figs. 16 to 18. The blade is shown at 38 and may or may not be transversely curved as desired, and at its inner end is integral with the base member comprising plate 39, at one edge of this plate. The base plate seats on the bottom of the recess 35 and it is provided with openings 40 and 41. Adjacent the opposite end of the plate from the blade 38 there is an integral rearwardly extending member 42 terminating in a clamping foot 43 which is bent'backwardly from the outer edge of the extension 42 at.43a and has an intermediate portion 44 located at one .side of the opening 41, the side of the opening facing this portion 44 being preferably open as shownat 45. The body of the clamping foot 43 is spaced inwardly somewhat from the plate 39 as shown in Fig. 16, but is provided with a lug 46 at its inner edge extending substantially to the plane of the lower face of the plate 39 and in alignment with the open side of the opening 41. The face of this lug and portion 44 are at substantially right angles to the center line through the center of the opening 41 and the recess 45, the foot 43 terminating at its free end in an angularly arranged portion 47-extending toward the plate 39 and on the opposite side from the open side 45 of the opening 41 and forming a stop and clamping lug for the lead wire as will later be described.

The clamping cam 48 is shown in Figs. 19 and 20 as provided with a pivot ing 49 on its inner side .and a channel 5.0 in the opposite or outer side to receive the bit of a screw driver or similar tool for turning the cam, and the edge of the cam comprises an eccentric curved "cam surface 51 eccentric to the pivot lug 49. The recess35 includes a deeper circularportion 52 in its bottom wall provided with a recess or socket 53 to receive thepivot stud 49 of the cam. to pivotally mount the cam in the recess, and this recess or socket is spaced to one side of the opening 36 for the lead Wire. Also to one side .of the recessed portion 52 there is a still deeper irregular recess 54 to receive the foot'4-3 of the contact element when this element isymounted .with the base plate 39 in the recess 35. This plate is mounted in the recess with the opening 40 :in alignmentwith an anchoring member 55 molded and anchored in the body member, and this may be a rivet as shown at 26in the first form to pass through the opening 40 and be rolledover onto the plate 39, or it could be a tapped element as shown to receive a securing screw 56 passing through the opening 49. Before mounting the plate in this position the cam 48 is placed in the depression 52 with its pivot lug 49 in the socket 53. It is therefore under the base plate 39and is held in the recess by thisplate under the [opening 41, which is smaller than thecam. When the plate 39and its associated parts are in this position the foot 43 isin the=depression 54 at the opposite side of the opening 36 for the lead wire from the cam, and therefore the lug 46 is also .on the opposite side of the open-ing 36 and its inner side is at 'right angles to the center line joining the center ofthe opening 36and the center of the pivot socket 53 and pivot 49 of the cam, as shown in Fig. 12.

In using the device the cam is turned'as indicated at the lower right hand of Fig 12 so that it is located outwardly of the opening 36. This leaves the opening free for insertion of the stripped or bared end 11 of the lead wire, or bundle of fine wires, and after this has been inserted through the opening 36 and past the cam, as shown in dotted lines in Fig. 15, it will be located between the edge of the cam and the lug 46 and against the inner surface of the foot 43 below this lug. Then by turning the cam to the right or clockwise, as viewed in Fig. 12, its eccentric cam surface will engage the lead wire or wires and'clamp it or them firmly against the lug 46 and inner wall of the intermediate portion 44 of the foot 43. The intur-ned end 47 .acts as a stop to prevent the vcam pushing the conductor wires off the lug 46 and the intermediate portion 44, so that the wires .are really=clamped against the lug 46, the intermediate portion .44 and the lug 47. As the surface of the lug 46 is at right angles to the line joining the centers of the opening 36 and the pivot 49 for the cam, there is no tendency for the pressure on the cam to rotate it in the reverse direction to release the lead wires. Therefore, in order to securely fasten the lead wires all that is necessary is to turn the cam to securely clamp the Wires and the cam will retain this clamping position. The conductor may be as easily released by merely rotating the cam in the opposite direction.

It will be understood from the above that the device is a very simple and effective one for clamping lead wires inserted through openings through the insulating body member from one side thereof to electrical contact elements on the opposite side by a simple quickly operated cam element, doing away with the necessity of Wrapping the band ends of the wires around the shank of a binding post screw and then setting up the screw, as the conductor wires are securely clamped by the cam.

Having thus set forth the nature of my invention, I claim:

1. In an electrical wiring device, an insulating body member, an electrical contact mounted on one side thereof comprising a base plate and an ear spaced from and below the plate by a connecting 'wall provided with a clamping surface, said plate and ear being provided with aligned openings adjacent said clamping surface for insertion of a lead wire to clamping position on said surface, a cam member pivotally mounted between the plate and ear and provided with a curved eccentric cam surface opposite said clamping surface to clamp the lead wire thereagainst by turning movement of the cam member, and means for turning the cam member to clamp the mm.

2. In an electrical wiring device, an insulating body member, an electrical contact mounted on one side thereof comprising a base plate and an ear spaced from and below the plate by a connecting wall provided with a clamping surface, said plate and car being provided with aligned openings adjacent said clamping surface, the body member being provided with an opening in alignment with said first openings leading from its opposite side for insertion of a lead wire to clamping position on said surface, a cam member pivotally mounted between the plate and ear and provided with a curved eccentric cam surface opposite said clamping surface to clamp the lead wire thereagainst by turning movement of the cam member, and means for turning the cam member to clamp the wire.

3. In an electrical wiring device, an insulating body member, an electrical contact mounted on one side thereof comprising a base plate provided with an extension on its under side provided with a clamping surface at substantially right angles to the plane of the plate, said body being provided with an opening leading from its opposite side at substantially right angles to the plane of the plate to adjacent said clamping surface for insertion of a lead wire to clamping position at substantially right angles to the plate, a substantially flat cam pivotally mounted under the plate parallel thereto and provided with a curved eccentric cam surface on its peripheral edge opposite said clamping surface to clamp the lead wire against this latter surface by turning movement of the cam, and said cam member being provided with means for turning it to clamp the wire.

4. In an electrical wiring device, an insulating body member, an electrical contact mounted on one side thereof comprising a base plate provided with an extension on its under side provided with a clamping surface at substantially right angles to the plane of the plate, said extension being bent laterally at one side of said clamping surface providing a stop lug, said body being provided with an opening leading from its opposite side to adjacent said clamping surface for insertion of a lead wire to clamping position, a cam pivotally mounted under said plate provided with an eccentric curved cam surface opposite said clamping surface to clamp the lead wire against said latter surface and the stop lug, and said cam being provided with means for turning it to clamp the Wire.

5. In an electrical wiring device, an insulating body member, an electrical contact mounted on one side thereof comprising a base plate provided with an extension on its under side provided with a clamping surface at substantially right angles to the plane of the plate, said extension being bent laterally at one side of said clamping surface providing a stop lug, said body being provided with an opening leading from its opposite side to adjacent said clamping surface for insertion of a lead wire to clamping position, said body being provided with a pivot socket under the plate, a substantially flat cam under the plate provided with a pivot lug seated in said socket to pivotally mount the cam and held in this position by the plate, said cam being provided with an eccentric curved cam surface opposite said clamping surface to clamp the wire against said latter surface and the stop lug by turning movement of the cam, and said cam being provided with means for turning it to clamp the wire.

6. In an electrical Wiring device comprising an insulating body member, an electrical contact mounted on one side thereof comprising a base member including a plate provided with an opening and a clamping surface located to one side of said opening and at substantially right angles to the plane of the plate, said body member being provided with an opening from its opposite side leading to said clamping surface at substantially right angles to the plane of the plate for insertion of a lead wire to clamping position at substantially right angles to the plate, and a substantially flat eccentric cam pivotally mounted at the under side of said plate and parallel thereto in alignment with the opening therein and provided with a curved cam surface on its peripheral edge opposite the clamping surface to clamp the lead wire against this latter surface.

References Cited in the file of this patent UNITED STATES PATENTS 948,596 Richter Feb. 8, 1910 1,328,784 Benjamin Jan. 20, 1920 1,960,191 Staub May 22, 1934 1,984,016 Gisske Dec. 11, 1934 2,103,548 Obermaier Dec. 28, 1937 2,388,724 Cornella Nov. 13, 1945 2,482,965 Cook Sept. 27, 1949 

